It's something of a no-win situation. If the Army are under general obligation to help the civil communities with things like flood defence (i.e. a MACC task), then of course the Army should hold the appropriate equipment (eg waders, boats etc). But you can't issue every soldier with a set of waders on the basis that sometime in his career he might be required to help in flood defence.
A central pool makes sense. The kit has to be dispatched from Donnington or wherever (Poole RNLI?) to where the issue is. Which of course takes time, and perhaps there are conflicting high priority demands for the same stores.
If the Police ever broke their no-strike law and went on strike, no doubt the Army would be called upon. But they don't have stab vests or handcuffs. I think a pick helve would do well as an ersatz truncheon though.
You're right, it's a mess, but not a mess that's easy to plan for.